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author Patrick J Volkerding <volkerdi@slackware.com>2018-05-25 23:29:36 +0000
committer Eric Hameleers <alien@slackware.com>2018-05-31 15:18:32 -0700
commit8ff4f2f51a6cf07fc33742ce3bee81328896e49b (patch)
tree4a166b8389404be98a6c098babaa444e2dec8f48 /patches/source/mkinitrd/README.initrd
parent76fc4757ac91ac7947a01fb7b53dddf9a78a01d1 (diff)
downloadcurrent-14.1.tar.gz
current-14.1.tar.xz
Fri May 25 23:29:36 UTC 201814.1
patches/packages/glibc-zoneinfo-2018e-noarch-2_slack14.1.txz: Rebuilt. Handle removal of US/Pacific-New timezone. If we see that the machine is using this, it will be automatically switched to US/Pacific.
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+
+Slackware initrd mini HOWTO
+by Patrick Volkerding, volkerdi@slackware.com
+@DATE@
+
+This document describes how to create and install an initrd, which may be
+required to use some features of the kernel. Also see "man mkinitrd".
+
+1. What is an initrd?
+2. Why to I need an initrd?
+3. How do I build the initrd?
+4. Now that I've built an initrd, how do I use it?
+
+
+1. What is an initrd?
+
+Initrd stands for "initial ramdisk". An initial ramdisk is a very small
+Linux filesystem that is loaded into RAM and mounted as the kernel boots,
+and before the main root filesystem is mounted.
+
+2. Why do I need an initrd?
+
+The usual reason to use an initrd is because you need to load kernel
+modules before mounting the root partition. Usually these modules are
+required to support the filesystem used by the root partition (ext3,
+reiserfs, xfs), or perhaps the controller that the hard drive is attached
+to (SCSI, RAID, etc). Essentially, there are so many different options
+available in modern Linux kernels that it isn't practical to try to ship
+many different kernels to try to cover everyone's needs. It's a lot more
+flexible to ship a generic kernel and a set of kernel modules for it.
+
+3. How do I build the initrd?
+
+The easiest way to make the initrd is to use the mkinitrd script included
+in Slackware's mkinitrd package. We'll walk through the process of
+upgrading to the generic @KERNEL_VERSION@ Linux kernel using the packages
+found in Slackware's slackware/a/ directory.
+
+First, make sure the kernel, kernel modules, and mkinitrd package are
+installed (the current version numbers might be a little different, so
+this is just an example):
+
+ installpkg kernel-generic-@KERNEL_VERSION@-@ARCH@-@BUILD@.tgz
+ installpkg kernel-modules-@KERNEL_VERSION@-@ARCH@-@BUILD@.tgz
+ installpkg mkinitrd-@MKINITRD_VERSION@-@ARCH@-@BUILD@.tgz
+
+Change into the /boot directory:
+
+ cd /boot
+
+Now you'll want to run "mkinitrd". I'm using ext4 for my root
+filesystem, and since mkinitrd should figure out any other modules
+it requires, I shouldn't need to specify any others:
+
+ mkinitrd -c -k @KERNEL_VERSION@ -m ext4
+
+This should do two things. First, it will create a directory
+/boot/initrd-tree containing the initrd's filesystem. Then it will
+create an initrd (/boot/initrd.gz) from this tree. If you wanted to,
+you could make some additional changes in /boot/initrd-tree/ and
+then run mkinitrd again without options to rebuild the image. That's
+optional, though, and only advanced users will need to think about that.
+
+Here's another example: Build an initrd image using Linux @KERNEL_VERSION@
+kernel modules for a system with an ext3 root partition on /dev/sdb3:
+
+ mkinitrd -c -k @KERNEL_VERSION@ -m ext3 -f ext3 -r /dev/sdb3
+
+
+4. Now that I've built an initrd, how do I use it?
+
+Now that you've got an initrd (/boot/initrd.gz), you'll want to load
+it along with the kernel at boot time. If you use LILO for your boot
+loader you'll need to edit /etc/lilo.conf and add a line to load the
+initrd. Here's an example section of lilo.conf showing how this is
+done:
+
+# Linux bootable partition config begins
+image = /boot/vmlinuz-generic-@KERNEL_VERSION@
+ initrd = /boot/initrd.gz
+ root = /dev/sda6
+ label = @LILO_KERNEL_NAME@
+ read-only
+# Linux bootable partition config ends
+
+The initrd is loaded by the "initrd = /boot/initrd.gz" line.
+Just add the line right below the line for the kernel image you use.
+Save the file, and then run LILO again ('lilo' at the command line).
+You'll need to run lilo every time you edit lilo.conf or rebuild the
+initrd.
+
+Other bootloaders such as syslinux also support the use of an initrd.
+See the documentation for those programs for details on using an
+initrd with them.
+
+
+---------
+
+Have fun!